1. Field of the Invention
The present invention relates to a vehicular disc brake having a caliper body that supports a brake piston so as to be axially slidably and has an electric motor, a speed reducer that reduces output from the electric motor, a motion converting mechanism that converts a rotation output from the speed reducer into axial operation force of the brake piston and is interposed between the brake piston and the speed reducer.
2. Description of Related Art
It is know in Japanese Patent Unexamined Publication JP-A-2001-263395 that vehicular disc brake having a motion converting mechanism that is disposed between a speed reducer for reducing power output from a motor shaft of an electric motor and a brake piston, and has axis line eccentric with the motor shaft In the vehicular disc brake, the speed reducer includes a pair of inner gears disposed in a pair of rotating members of the motion converting mechanism or the motor shaft; and a pair of outer gears disposed in the other of the pair of rotating members or the motor shaft so as to engage with the inner gears.
However, in the vehicular disc brake disclosed in JP-A-2001-263395, a ball bearing is interposed between the outer circumference of at least one of the pair of inner gears of the speed reducer and a casing for housing the speed reducer. Thus, a space for the ball bearing is required in outside the inner gears in the radius direction, thereby causing an increase in size of the speed reducer.